Telephone-transmitter.



C. ADAMS-RANDALL.

TELEPHONE TRANSMITTER.

APPLIUATION FILED APR. 16. 1907.

927,395. Patenteq July 6,1909.

2 SHEETS-SHEET 1.

(id/5&6 (4%1116 :Rarula 73 G. ADAMS-RANDALL.

TELEPHONE TRANSMITTER. Arrmoxnon FILED APR. 16. 1907. 7

927,395. Patented Ju ly e, 1909.

2 SHEETS-SHEET 2.

Eben fan I o an induction adapted, as is well known, to the use ofhightageously therethrough a current of To all whom it may concern:

CHARLES ADAMS-RANDALL, OF NEW YORK, N. Y.

PATENT OFFICE.

TELEPHONE-TRANSMITTER.

Be it known that I, (hm-anus AnAMs-RA-N- BALL, a. citizen of the United,States residing at New York, in the county" of New York and State of NewYork,'have invented new and useful I1n rovenients in Telephone-Tran-sniitters, o specification. i, r

In telephony, telephone transmitters, as now generally constructed andused in a local circuit with the battery and primary coil ortransformer, are not tension currents, or currents of high Voltage,

} the ractical' maximum voltage therethrough six voltsat an amperageusually very small, determined by the re-' rare y exceeding sistanceofthe circuit of which. the trans mitter is a{ part. This low voltagehasbeen found to be absolutely necessary to overcome the troublesarising from the use of too high voltage which causes arcing, frying andheating in and of the variable resistance of thetransmitter, creatingdisturbing noises in the receiver, affecting the articulation, theadjustment and reliability of the transmitter, and destroying theefiicienc of the variable resistance in' a-very short t me.

The object of the present invention is to produce a telephonetransmitter havin and novel means and general construction t0 adapt thesame to carry and vary advanhigh voltage, as compared with thevoltage'heretofore used and without the above noted dis' advantages anddefects,

and especially overcoming deterioration of the variable resistance,such-telephone transmitter, becaus of' the greatly increased voltagecarried and varied thereby,beiug applicable for practical use on longerline and cable circuits than has heretofore been possible withtransmitters as now constructed. ,7

To this end the in vention generically consists in obtaining greatlyincreased voltage or watts through a telephone transmitter, by

having a variable resistance conductor of and large CQHdllCtlVltY lownorlnal resistance or current carrying capacity; supporting saidvariable resistance cw, 'rzmssc directly upon a suitable vibrator, suchas a diaphragm, or upon or within some part se-i cured to the diaphragmand vibrated thereby} holding and confining en masse under pressure,said variable resistance having a materially increased of low resistanceSpecification of Letters Patent. Application filed April 10, 1907.Serial No. 368,467.

which the following is a Patented July '6, 1909.

. and large conductivity within a suitable receptacle andcoveringthisresistance with a.

thin yielding perforated plate or cover of anon-conducting materialhaving a contact piece or electrode, or electrodes, preferablyadjustable, in electrical contact with i the mass of resistance granulesthrough a pen foration, or perforations, in the said'nonconduct'in plateor. cover; and having a single lead or connection from one pole orbattery or other source of electrical energy, such as an other sourcecontact pieces are the transmitter.

in a mass over a comparatively large sur ace covering, preferably at asuitable uniform depth or thickness, almost the entire surface and'ifsuch support be used it the granu es,

the diaphragmand vibrated is attached to thereby.

,w-i-th the part carrying the same and being the means for makingelectrical connection to thegranules from the battery or other side,face, or surface of the granules is covpoint or points of conered exceptat the tact therewith, by a thin yielding or pliable perforation, or ani'iinber of perforations, formed therein, and further covered by asuitably supported or preferably adjustable contact piece'or piecesarranged over the cover andv granules and resting on the edge of theperforation or perforations therein, whereby the granulesarc entirelycovered, confined and held, under pressure in a mass, the contact pieceor pieces being in proper trical connection or connections from the ortwo or more transformers if two or more used in the construction of V 0fthe diaphragm or other support carrying source of electrical energy. Theopposite plate of mica, paper, rubber, or other similarnon-conductingmaterial havlng a central electric light current supply, to the mass ofconfined granules, and therefrom such circuit including, if

.Toobtaiu the increased conductivity of the 1 variable res stance, thegranules are arran ed .80

\8'5 The granules are suitably held in W place by an annular body,preferably ofsomeas leather,-paper, soft or surface of the granules bemgin electrical contact ioo engagement therewith and forming theelecbattery to the adjacent side or surface of the granules.

In the drawings: Figure 1 represents a transverse vertical section ofthe transmitter and the circuit connections in diagrammatic plan. Fig. 2is a top plan view of a portion of the transmitter. Figs. 3, t and'5 aredetail views of the .transmitter. Fig- 6 is a plan View, partially indiagram, of a modification of the transmitter. Fig. 7--is a detail 'planview of a portion of the transmitter shown by Fig. 6.

Similar characters I of reference are? employed to indicatecorresponding parts in the several views.

, The numeral 1 represents the case or body as at 5 and fitting in andengaging the inner screw-threaded surface 6 of the case or body 1. Thering 5 is provided with three or more lugs 0r projections 7 which bearupon the peripheral edge of the diaphragm at different portions of thelatter and by means of which greater freedom of vibration of thediaphragm is obtained than when a clamping means is employed completelyengaging the peripheral edgeof the diaphragm. An annular receptacle orbody 8, formed of suitable pliable material such as soft leather,rubber, felt or the like, is secured to the diaphragm by means of glue.orotherwise, and preferably has an outer diameter nearly equal to thatof the diaphragm, the inner diameter of this annular receptacle or bodybeing greatly in excess of the diameter or area of the face of theelectrode or electrodes employed in the organization of the transmitter.The body 8 forms a cup, chamber, or holding means having a"comparatively large superficial area of such suitable depth as topermit the use of a mass of granular variable resistance material oflarge conductivity and low normal resistance.

The variable resistance9, preferably composed of carbon granules, isarranged within the annular receptacle or body 8, the said granules ina' mass entirely filling the body or receptacle at a uniform depth. Thisvariable resistance is held and confined under pressure within theannular receptacle or theannular receptacle or body 8 by means ofshellac, glue, or other material and is also held close to theresistance material by a contact piece 11, as shown by Fig. l, the saidcontact piece resting upon the cover 10 over a perforation 12 in thecenter of the cap or cover, the said contact 11 positively engaging thegranules 9 at all times and completing the -inc1osure for the variableresistance to confine the latter within the receptacle provided by thebody 8. The contact piece 11 is carried by a suitable arm' 13 attachedto the case or body 1 at its outer extremity, as at 14, and having aslight adjustment through the medium of a stiff arm or member 15 alsofixed to the case 1 andextending over the arm 13 and carrying anadjusting screw 16 which bears on the inner end or extremity of the arm13. By adjusting the screw 16 the engaging pressure of the contact piece11 with relation to the cap or cover 10 and the. variable resistancegranules 9 may be modified.

' A mouth piece 25 is provided which is secured to the case 1 by ascrew-thread upon the same fitting into the screw-threaded centralopening 26 of the said case.

-A suitable cap or cover 27 is applied over the transmitter opposite themouth piece so that all the parts of the transmitter are fully inclosed,the cover being removable through the medium of screw-threads formed ina portion thereof and engaging corresponding threads on the exteriorsurface of the case of body 1, as at 28.

The circuit connections with the battery B to and from the transmitterare shown by Fig. 1, and are as follows: A wire 'w runs from thepositive terminal of the battery to the primary coil of an inductioncoil 17, the said primary coil also being connected to the diaphragm 4and variable resistance 9 by a wire 18 passing through an opening 27 inthe center of the transmitter cap or cover 27. The secondary coil of thesaid induction coil 17 is connected to line L in the usual manner, asshown by Fig. 1, and also to ground by a wire 'w. A switch S is used todetermine and change the voltage of the current through the transmitterand has thereon a series of buttons A, C, D and E with which a switcharm S is adapted to cooperate, and between the pivotal extremity of thislatterv arm and the arm 13 carrying the contact piece 11 a wire 19 runsto setup the proper electrical connection between-the switch and thesaid contact piece.v The but- I 'v0lts,as shown, or up to the the arm orsupport 13 andby wire 19 to the through the granules composing thevariable reslstance to thecont'actpiec'e 11, through switch S and fromthe latter back to the bat tery in accordance with the button engaged bytheswitch arm S.

a As before indicated, the switch S provides convenient means forchanging the voltage from maximum or twenty-four volts, for instance,when the button A engaged by the switch arm S; eighteen volts when thebut-. ton (l is included in the circuit; twelve volts when the buttonDhas the switch arm thereon andtosix volts when the button E is in thecircuit, or. per contra, increased from the minimum to the maximum,twenty-tour reatest possible maximum that may be used with a transmitterconstructed in accordance with-the princi'ples'of the improvedtransmitter.

The switch S, as shown, has-but four'contact buttons; but it will beunderstood that the same may have a "greater number it required for stll further sub-dividing the bat-- tery or for use with a battery havinga larger number of cellsand .a greater number of sub-divisionsthan'illustratedby Fig. 1. The

desired.

invention is not limited to the use'of a switch, the latter being shownasa simple illustration of one means for sub-dividing the battery, butin -lieuof theswitc'h other means,either automatic or semi-automatic,maybe used without departing from the principle involved or to controlthe sub divisions of the battery. to determine the vgltagethrough thetransmitter as may be Tlie transmitter shown by Figs. 1, 2, 3, 4 and 5,illustrates the-simplest and preferredform of the invention.Thissimplified form of the inve1ition may, however, beyaried in manyways, one modification being shown by Figs. (3

just dtscribed and as and 7 and consisting in providing more than oneperforatlonm the cover or cap 10, the

latter in this modified construction having a,

series of three openings 29 therein to accommodate acorresponding numberof electrodes or contact; pieces 11, 11"v and 11 carried by supportingarms 13, 13? and 13 secured to the case 1,. as clearly shown byFig. 6.In i connection with this modified formof the invention it is preferredto employ three induction coils 17, 17".and 17, connected respectivelyfrom one side of theprimary coils to the arms 13, 13, 13", and theelectrodes 1,1", 11, 11, the granules 9, the diaphragm 10, and by wire'31to the battery B,

the opposite ends of the primary coils being connected in multiple by awire 30" to'the switch arm S and from the buttons A, C, D and E to thebattery B by wiresQQ, '21, 22

to the construction shown by Fig. 1. The in-'. side and outside wires 0*the secondary coil of and 23 in all respects similar in'arrangement' 1As heretofore indicated, the important features of the present inventionto be particularly noted and compared with other granular transniitteisare the extendcdor increased mass of granules of low normal resistanceand increased current carrying or 1 conducting capacity, meansfor'holdingand confining the granules. in a mass under pressure, and thelargely increased surface of the granules ascompared with the actualvariable surface of the contact .or contacts 00- operating therewith andin electrical contact with the granulesat the contact surface thereof ofsmallest area. These particular es 'sential features of theiinventionpermit of the eil'ective use of a current of minimum yoltage, or a lowvoltage of .six volts or'less as generally employed as a jmaximum inknown granulartransmitters, and also per hit of the practical commercialuseof a current at a voltage many times greater than the minimumspecified u ith'correspoiicliiigincreased results, of benefits andadvantages hereinbefore noted and'particularly producing a greatervolume of tone at the receiver and the operation of more difficultcircuits, andcircuits of greater length than hereto fore possible andwithout the detrimental effects of arcing frying undue heating ordeterioration "ofthe variable resistances heretofore experienced intheoperation of telephone transmitters.

Having thus described the mvention, what is claimed, is: I

- A telephone transmitter constructed and adapted to carry and vary highor low tension currents therethrough comprising a diaphragm or othervibrating medium in electrical contact with; andcarrying or supporting aconfined variable resistance con dnctor of'uniform depth and largeconduct ring capacity, the conductor being held upon the diaphragm .orvibrating medium in a mass under ressure, acoiiperating electrode orcontact means .in adjustable"electrical contact with the variableresistance conductor, a source of current supply, and connectionstherefrom to thevariable resistance conductor and to "the cooperatingelectrode.

*QQA telephone transmitter constructed andi'adapted to carryand varyhigh or low tension currents therethrough,comprising a diaphragm orother vibrating medium car- .rying or supporting a confined variableresistance of uniform depth, low resistance and large conductingcapacity held in a confined mass under pressure in direct contacttherewith, a cooperating electrode in adjustable electrical contact withthe variable resistance, and a source of current supply havingconnections with the variable resistance conductor and the cooperatingelectrode.

3. A telephone transmitter constructed and adapted to carry and varyhigh or low tension currents therethrough, comprising a diaphragm orother vibrating medium in electrical contact with and carrying orsupporting a confined variable resistance granular material of uniformdepth, low resist ance and large conducting capacity held confinedthereon in a mass under pressure, the variable resistance granularmaterial directly contacting with the diaphragm or othervibratingmedium, a cooperating electrode in adjustable electricalcontact with the variable resistance, a source of current supply havingconnections with the variable resistance conductor and the cooperatingelectrode, an induction coil having its primary in circuit-with thecurrent supply and the transmitter and its secondary in circuit with theline, and means in circuit in series with the current supply,thetransmitter, and the induction 0011 primary for increasin anddecreasing the current supply in sald circuit.

4. A telephone transmitter constructed and adapted to carry and varyhigh or low tension currents passing therethrough, comprising incombination, a diaphragm or other vibrating medium, a variableresistance conductor, a receptacle on the diaphragm or vibrating mediumand having a non-metallic cover which is partially open and containingthe said variable resistance conductor-in a confined mass underpressure, an electrode means in electrical eontact with the variableresistance conductor through the partially open non-metallic cover andcooperating therewith and with the diaphragm or vibrating medium, asource of current supply, and connections from the source of currentsupply to. the variable resistance conductor and to the cooperatingelectrode and increased current carrying or conduct" iug capacity andhaving direct contact with the vibrating medium, an electrode or contactpiece in electrical contact with the portion of the resistance mediumthrough the cover opposite the portion of said medium with which thevibrating medium is in direct contact, the resistance medium having asurface largely in excess of that of the electrode or contact piece, abattery means having one pole connected to the electrode or contactpiece, and means for connecting the other pole of the battery means withthe surface of the variable resistance medium opposite the electrode orcontact piece.

6. A telephone transmitter having in combination a vibrating medium, areceptacle on tl e medium provided with a non-metallic eovei'which ispartially open, a variable resistance medium confined in the receptacleunder pressure and exposed to the partially open portion of the cover,the receptacle and variable resistance medium being vibratingly movablewith the vibrating medium, one or more electrode devices in directelectrical contact with the variable resistance through the partiallyopen portion of the cover, a battery, and electrical connections betweenone pole of the battery and theone or .more electrode devices and theremaining pole of the battery and the opposite side of the variableresistance.

7. A telephone transmitter having in combination, a vibrating medium, areceptacle held by the vibrating medium and provided with a cover ofmica having one or more openings therein, a variable resistance meansconfined in the receptacle in direct engagement with the vibratingmedium, one or more adjustable spring supported electrodes in pressurecontact with the variable resistance means through the open cover, abattery or other source of electric energy supply, and means forelectrically connecting the variable resistance and the one or moreelectrodes to opposite poles of the battery.

8. A telephone transmitter having in combination a diaphragm, areceptacle supported and in part formed by the diaphragm and consistingof an annular pad or washer and a perforated non-metallic cover, avariable granular resistance means confined in the said receptacle, anelectrode means in con tact. with the variable; resistance means throughthe perforated cover, a source of electric energy, and electricalconnections between the source of electric energy and the variablegranular resistance and electrode means, the variable granular resist-'ance having a larger surface area than the electrode means in contacttherewith.

9. The combination, in a telephone transmitter, of a diaphragm having areceptacle thereon, a variable resistance material held in a mass withinthe receptacle and in direct contact with the diaphragm, a perforatedcover of nonconducting material on the receptacle. an adjustableelectrode in variable electrical contact with the variable resistancematerial and slightly impinging or hearing on the cover around theperforationand acting with the cover to completely confine the variableresistance material Within the receptacle, and a source 0f-e1ectricenergy supply in electrical connectionwith the electrode and variableresistance material. I

10. In a telephone transmitter, a vibrating means, a granular variableresistance conductor held confined under pressure, electrode means incontact with said conductor,

and means inde endent of the electrode means and the vi rating means forplacing pressure on the resistance conductor.

duct'or, a yieldin or pliable non-conducting co'ver confin1ng 1eresistance conductor un der initial pressure, and electrodemeans in'co1itactxvith the resistance conductor and having a smaller area thanthat of the said resistance conductor. 7 In testimony whereof I havehereunto setmy hand in presence of two subscribing witnesses. v

CHARLES ADAMS -RANDALL. Witnesses:

DANIEL D. LOVELACE, AnG. HETHERLIN.

